okay, i had to flash my n900 due some playing around with nitdroid...
I tried the Fiasco image alone and still it came up with errors. So finally I had to flash the Vanilla emmc image also.

What I want to know is, is there ANY way to recover atleast part of my lost contacts/conversations? For computers, there are programs that can recover files/partitions even after formating. Is such a thing possible for the n900?

Please help me!

Mount it from a PC and run a recovery tool.
You might need to use PhotoRec to do it, as reflashing wipes over the file table.

Should be possible if you connect to USB in mass storage mode, then use a PC data recovery program that supports USB devices.
http://www.piriform.com/recuva is a good start.

but in mass storage mode, i can access only the 27gb partition. I cant access the 2gb partition where we contacts/conversation is stored, right?

Hi there is photorec and testdisk file recovery ported for maemo here
http://maemo.org/packages/view/recovery-tools/

I think the best way would be to flash the rescue kernel, this way you're nt overwriting any data on the partition.

Backupmenu also gives you USB Mass storage mode access to the /home partition, but if you haven't already had it installed, it might (I'm not sure if it does or not, but maybe maemo would during the time it takes while the device is on and you are installing it) perform some writes to the partition.

as others have said, use testdisk directly from your phone. there's already a maemo port for it
but I doubt you can recover your contacts/conversation db though. as you've said, it's possible to recover data from formatted disk on PC. but problem is, you're not only formatting. you're copying new data to the same disk with flashing, so chances are those disk sector where your files were located has been overwritten by other files, and it's impossible to recover using software only
but it's not hurt to at least try though

Deleted files are not gone until the disk needs to write new data, and will only overwrite old files if it needs that space to do so.
Myjad provide powerful data recovery software!

Please, if you are resurrecting a 2.5 years old thread, then at least get your facts right. There is no preference for overwriting deleted old files when writing new data. There is preference for overwriting existing files when writing new data to an existing file, but that is a different thing.

None of that matters though to the OP's case. For two reasons. First, his case is after flashing. Which is somewhat similar to reformatting your regular hard drive. All the information about the original data layout is gone and writing new data starts from the beginning. The OP might get lucky if the data he wants to recover was written towards the end of the disk and writing new data has not reached that point yet, but I would not hold my hopes too high.

The second reason is that the data storage in the N900 is not a regular hard disk. It is It is a flash memory. Flash memory is organized in blocks, just like your regular hard drive. The difference is that updating a flash memory block involves one extra step: deleting old data. This is not needed on magnetic media, they just overwrite the old data. Flash media, however, can only write zeroes. They have no way of turning zeroes back to ones other than by erasing the entire block and turning all bits in the block to ones, then writing the updated block back. Erasing is a relatively lengthy operation and flash media prefer to avoid it if they can, which means they rather write the updated data to a brand new, unused block and mark the old one for erasing later. This is implemented at the hardware level, below even the level that the kernel can reach.

There are of course differences in details of how this is implemented in any particular flash memory make or model, but the upshot is that after a few writes, you have no idea where any data block is physically stored. The only one who knows that is the flash memory controller itself.

So claims such as "disk will only overwrite old files if it needs space" are rather dubious. The OP may or may not be lucky to recover his data, but the chance has more to do with wear leveling than anything else.